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MRI vs. CTA Prior to Endovascular Stroke Treatment
Study Questions:
How does magnetic resonance imaging (MRI) compare to computed tomography angiography (CTA)-based patient selection for patients undergoing endovascular stroke treatment?
Methods:
Using a registry of consecutive stroke patients, admitted to 15 stroke centers in Korea, the authors identified patients treated with endovascular therapy for anterior circulation infarcts between April 2008 and May 2015. The decision to proceed with endovascular treatment was made based on MRI or CTA imaging. This study compares the functional outcome at 3 months, measured by the modified Rankin scale, of patients selected for endovascular treatment by MRI versus CTA. Statistical models were adjusted for clinical, radiographic, and time factors that are associated with functional outcome.
Results:
There were 38,566 patients in the registry and 1,265 were included in the study. The patients’ average age was 69 years, and 53% were male. The median initial National Institutes of Health Stroke Scale score was 15, 66% had successful reperfusion after endovascular treatment, and 37% had a good functional outcome at 3 months. Twenty-two percent of patients had CTA imaging prior to endovascular treatment and the remainder had an MRI. There were marked differences between the CTA and MRI groups. The CTA group had more severe strokes, were more likely to have diabetes and atrial fibrillation, less likely to have perfusion imaging, and less likely to have good recanalization after endovascular treatment. However, the patients in the CTA group were more likely to receive intravenous thrombolysis and were reperfused faster than the MRI group.
Functional outcome at 3 months did not differ between the CTA and MRI groups (38.5% vs. 38.1% with a good functional outcome, p = 0.92), and adjustment for prognostic factors did not change this result. Patients in the MRI group had a lower risk of intracerebral hemorrhage (7.7% vs. 3.8%, p = 0.01). There was no difference in mortality between the groups (adjusted odds ratio for MRI [vs. CTA], 0.61; 95% confidence interval, 0.37-1.00).
Conclusions:
MRI-based selection of patients for endovascular stroke treatment was not associated with a difference in functional outcome when compared to CTA-based selection, although the risk of intracerebral hemorrhage was lower.
Perspective:
Endovascular stroke treatment is associated with a tremendous improvement in functional outcome, in appropriately selected patients. While MRI can provide more accurate characterization of the ischemic core and penumbra, the additional time needed for workflow and imaging acquisition can be problematic in a time-sensitive disease such as acute ischemic stroke. This study found that despite taking additional time, MRI-based patient selection was equivalent to CTA-based selection when the authors looked at 3-month functional outcome. These results are intriguing; however, they should be interpreted with care. This was a registry-based study and there were notable, clinically important differences between the patients who underwent selection with CTA versus MRI. Additionally, there was no uniform protocol used to select patients for endovascular treatment based on imaging data. The study was also was performed during a time period before endovascular stroke treatment became the standard of care.
While the decreased risk of intracerebral hemorrhage associated with MRI-based patient selection is important, without a difference in functional outcome, and with the increased time and lack of widespread availability of acute MRI scanning, until there are additional data, CTA-based patient selection for endovascular stroke treatment will likely continue to be the preferred option.
Clinical Topics: Arrhythmias and Clinical EP, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Prevention, Atrial Fibrillation/Supraventricular Arrhythmias, Interventions and Imaging, Angiography, Computed Tomography, Magnetic Resonance Imaging, Nuclear Imaging
Keywords: Atrial Fibrillation, Brain Ischemia, Cerebral Hemorrhage, Coronary Angiography, Diabetes Mellitus, Diagnostic Imaging, Endovascular Procedures, Magnetic Resonance Imaging, Myocardial Perfusion Imaging, Reperfusion, Secondary Prevention, Standard of Care, Stroke, Tomography, X-Ray Computed, Vascular Diseases
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